Stent delivery apparatus and method

ABSTRACT

A delivery system for implantation of a self-expanding stent in a vessel consists of an elongate flexible catheter for delivering a self-expanding stent to a predetermined location in a vessel. The stent surrounds the flexible catheter near its distal end and is held in a delivery configuration where the stent has a reduced radius along its entire axial length by a stent retaining and release means. The stent retaining and release means is either one or more slipping sleeves which either contain the stent themselves or form a waterproof chamber with the stent being contained by water soluble bands or swelling bands. The stent retaining and release means can also be a pair of sleeves connected to hydraulic pistons, or a pair of sleeves connected to push/pull wires.  
     An alternate embodiment of the delivery system uses a stent retaining and release means which is a single layer sheath retaining sleeve means for retaining the stent in its delivery configuration attached to a slipping sleeve means for releasing the stent to self-expand. A balloon may optionally be used to seat the stent in the vessel after self-expansion. The stent may also optionally be retained by water soluble or swelling bands.  
     Another alternate embodiment of the delivery system is described where the stent is held in its reduced delivery configuration by a swelling band stent retaining and release means for retaining the stent in the delivery configuration and for deploying the stent, comprised of at least one band made of a water swelling material, which holds the self-expanding stent it its delivery configuration against the outwardly urging force of the self-expanding stent until fluid swells the band, thereby releasing the stent to self-expand.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a delivery system and method fordelivering and deploying a stent. More specifically, the inventionrelates to a delivery system and method for delivering and deploying aself-expanding stent in a body lumen.

[0003] 2. Description of the Related Art

[0004] Stents and delivery systems for deploying stents are a highlydeveloped and well known field of medical technology. Stents have manywell known uses and applications. A stent is a prosthesis which isgenerally tubular and which is expanded radially in a vessel or lumen tomaintain its patency. Stents are widely used in body vessels, bodycanals, ducts or other body lumens.

[0005] The preferred present stent delivery apparatus and methodutilizes a self-expanding stent, which is well known in the art. A wellknown self-expanding stent is the woven braided stent disclosed in U.S.Pat. No. 4,655,771 (Wallsten); U.S. Pat. No. 4,954,126 (Wallsten) andU.S. Pat. No. 5,061,275 (Wallsten), although any type of self-expandingstent may be deployed using the inventive delivery system and method.The delivery system of the present invention may also be used to delivera balloon expanded stent and may also deliver stent grafts, which arewell known in the art.

[0006] The delivery systems for stents are generally comprised ofcatheters with the stent axially surrounding the distal end of thecatheter. It is highly desirable to keep the profile of the catheter assmall as possible. Therefore, self-expanding stents are generallyconfined in a reduced radius for delivery to the deployment site. Oncethe stent is deployed the catheter is removed, leaving the stentimplanted at the desired location to keep the vessel walls from closing.

[0007] A variety of techniques have been developed for holding aself-expanding stent in its reduced configuration while moving thedistal end of the catheter to the deployment site. For example, in U.S.Pat. No. 4,655,771 (Wallsten), gripping members at either end of thestent hold the stent in an axially-elongated position, which causes thestent to take a reduced radius delivery configuration.

[0008] Another common technique for maintaining the self-expanding stentin a reduced radius delivery configuration is using a sheath whichsurrounds the stent and compresses it around the catheter. Thistechnique is disclosed in U.S. Pat. No. 5,071,407 (Termin) and U.S. Pat.No. 5,064,435 (Porter), both of which use a silicon rubber sheath tocompress the stent. A similar technique is disclosed in U.S. Pat. No.5,026,377 (Burton) and U.S. Pat. No. 5,078,720 (Burton).

[0009] A variation on surrounding the stent with a sheath is disclosedin U.S. Pat. No. 4,732,152 (Wallsten); U.S. Pat. No. 4,848,343(Wallsten) and U.S. Pat. No. 4,875,480 (Imbert), all of which discloseusing a sleeve formed of a doubled-over section of membrane to compressand contain the stent.

[0010] U.S. Pat. No. 5,234,457 discloses using a sheath to surround amesh stent of the type disclosed in U.S. Pat. No. 4,922,405. However, inthis patent the sheath is not used to compress the stent, but is used toprevent fluid from accessing the stent. The stent is impregnated with apure gelatin or other dissolvable material which, when cured, hassufficient strength to hold the stent in its reduced deliveryconfiguration. Once the sheath is withdrawn, the stent is exposed to thebody fluids which dissolve the gelatin, allowing the stent toself-expand. This reference also discloses using axial distribution ofgelatins with different rates of thermal decomposition to control thephysical profile of the stent as it expands. However, using animpregnated mesh stent adds several inconvenient manufacturing steps tothe process of preparing the stent for implantation.

[0011] All of the methods for delivery of a stent discussed to thispoint involve releasing the stent starting from one end of the stent,except for Anderson U.S. Pat. No. 5,234,457 which can allow the stent toself-expand uniformly over its entire length. An improvement to thistype of deployment is discussed in Heyn U.S. Pat. No. 5,201,757 whichrelates to medial deployment of a stent. Medial deployment of a stentreleases the middle region of the stent before releasing either end ofit. This tends to prevent stent movement during deployment.

[0012] All of the prior art methods of containing and deploying theself-expanding stent have several problems. First, many of thetechniques require that movement of the entire sheath or exteriorcatheter take place to manipulate the distal end of the catheter andeffect release of the stent. This can be seen in Wallsten U.S. Pat. No.4,655,771 and Wallsten U.S. Pat. No. 4,954,126 in which tubular member23 is moved forward from position 22 to position 30. In Termin U.S. Pat.No. 5,071,407 the sheath 32 is withdrawn proximally with respect to thestent. In Porter U.S. Pat. No. 5,064,435 the sheath 38 is withdrawnproximally with respect to the stent. Burton U.S. Pat. No. 5,026,377also moves an outer sleeve backwards relative to the stent. In WallstenU.S. Pat. No. 4,732,152; Wallsten U.S. Pat. No. 4,848,343, and ImbertU.S. Pat. No. 4,875,480, a hose 5 is connected to a maneuvering tube 8which runs the length of the catheter. Finally, in Heyn, finger grip 5,connected to section 58 causes outer catheter 20 and sleeve 24 to moveproximally relative to the stent.

[0013] In all of the cases discussed above, movement occurs over theentire length of the catheter between the proximal end controlled by thephysician and the distal end where the stent is released. This cathetermovement in the vessel creates several problems. First, cathetermovement can disturb or move the introducer sheath at the wound sitewhere the catheter is inserted into the vessel. Secondly, in tortuousanatomy the added friction caused by rubbing the outer catheter againstthe vessel, as well as the added friction created between theinner/outer layer interface, can make deployment difficult. Thetranslation of control movements from the proximal to the distal end isimprecise, jerky and in some instances impossible due to the increasedfriction caused by tortuosity. Thirdly, it can create trauma to theendothelium over the entire length of the catheter.

[0014] Another drawback to the prior art stent delivery systemsdiscussed above is that requiring an extra sheath layer, sleeve layer orlayered catheters (Heyn) increases the profile of the catheter, which isundesirable. The Heyn device described in U.S. Pat. No. 5,201,757 has aprofile of 0.12 inches (3.048 mm). A reduction in profile of even 1F(French) is considered significant to those skilled in the art.

[0015] There remains a need in the art for a stent delivery system inwhich the catheter remains stationary in the vessel and movement isconfined to the distal end of the catheter to avoid disturbing theintroducer sheath, minimize trauma to the endothelium and allow for moveeasier and more accurate deployment in tortuous anatomy. Furthermore,there remains the need for a stent delivery catheter with a smallerprofile than the prior art. There is also a need for an improved form ofmedial release.

SUMMARY OF THE INVENTION

[0016] The inventive stent delivery device includes a catheter with astent held in a reduced delivery configuration for insertion andtransport through a body lumen to a predetermined site for deployment ofa stent, self-expanding stent, stent graft or the like. An embodimentutilizes a pair of slipping sleeves, each being a section of membranefolded over onto itself, which can either hold a self-expanding stent inthe delivery configuration or form a watertight chamber for an enclosedholding means. When the slipping sleeves are used to form a watertightchamber, the stent is held in the delivery configuration by means of atubular sleeve made of water soluble material; a plurality of bands madeof water soluble material, swelling band(s) or other degradablematerial. A related embodiment can utilize only a single slipping sleevein a non-medial release form.

[0017] An alternate embodiment of the stent delivery device includesseparate lumens, each containing a teflon or hydrophilic coated wireextending to respective proximal and distal movable sleeves. Thephysician can individually control each sleeve by pulling on the wireconnected to the proximal sleeve and/or pushing on the wire connected tothe distal sleeve. A related embodiment can utilize only a single sleevein a non-medial release form with a single wire.

[0018] In another embodiment of the stent delivery device, the separatelumens each contain proximal and distal pistons which are connected byteflon or hydrophilic coated wires extending to their respectiveproximal and distal sleeves. The lumens are connected by a fluidcommunication port, which is positioned such that the distal piston mustmove distally a predetermined distance before the fluid can access theport and flow into the proximal piston lumen, where it moves theproximal piston proximally. This causes a form of medial release inwhich the distal sleeve releases the distal end of the stent prior torelease of the proximal end.

[0019] This application also discloses another embodiment called thesingle layer sheath stent delivery apparatus and method, which is animprovement of applicant's co-pending improved stent delivery apparatusand method application, filed Oct. 22, 1993 as Ser. No. 08/141,269. Theentire contents of Ser. No. 08/141,269 filed Oct. 22, 1993 are herebyincorporated by reference.

[0020] The inventive single layer sheath stent delivery deviceembodiment includes a catheter with a stent held in a reduced deliveryconfiguration for insertion and transport through a body lumen to apredetermined site for deployment of a stent, self-expanding stent,stent graft or the like. This embodiment utilizes a slipping sleeve,which is a section of membrane folded over onto itself, with a singlelayer sheath attached to the slipping sleeve which can hold aself-expanding stent in the delivery configuration. Fluid is insertedinto the slipping sleeve through a fluid access port, and the pressurecauses the slip seal end of the slipping sleeve to move axially awayfrom the stent, retracting the single layer sheath attached to theslipping sleeve, thereby releasing the stent to self-expand. Theinvention will also deliver non self-expanding stents by placing thestent around an expandable balloon. Once the single layer sheath isretracted, the balloon is expanded to expand the stent.

[0021] An alternate embodiment of the single layer sheath stent deliverydevice provides medial release by using two single layer sheaths toretain the stent in the delivery configuration, each being attached to aslipping sleeve. Fluid pressure causes both slipping sleeves to moveaxially away from the stent, retracting their respective sections ofsingle layer sheath to release the stent for self-expansion or balloonexpansion.

[0022] Another alternate embodiment of the invention is a deliverysystem for implantation of a stent in a vessel, which includes anelongate flexible catheter having proximal and distal ends fordelivering a self-expanding stent to a predetermined location in avessel, the self-expanding stent having proximal and distal ends, thestent being in a delivery configuration where the stent has a reducedradius along its entire axial length and where the stent is held in itsreduced delivery configuration by a swelling band stent retaining andrelease means for retaining the stent in the delivery configuration andfor deploying the stent, comprised of at least one band made of a waterswelling material, which holds the self-expanding stent in its deliveryconfiguration against the outwardly urging force of the self-expandingstent until fluid swells the band, thereby releasing the stent toself-expand.

BRIEF DESCRIPTION OF THE DRAWINGS

[0023] A detailed description of the invention is hereafter describedwith specific reference being made to the drawings in which:

[0024]FIG. 1 is a side elevational section showing a stent deploymentdevice with the slipping sleeves shown with the stent in the uncoveredposition, and with the stent held in a confined or reduced deliveryconfiguration with a plurality of water soluble bands;

[0025]FIG. 2 is a side elevational section fragment of FIG. 2 showingthe slipping sleeves of FIG. 1 in the covered position;

[0026]FIG. 2A is a fragment of FIG. 2 showing an alternate embodiment ofthe slipping sleeve inflation of FIG. 2;

[0027]FIG. 2B is a fragment of FIG. 2 showing an alternate L-sealembodiment of the slipping sleeve;

[0028]FIG. 3 is a side elevational section of the distal end portion ofa deployment device showing the slipping sleeves of FIG. 2 retracted andwith the middle bands dissolved;

[0029]FIG. 4 is a showing similar to FIG. 3 illustrating a firstalternate embodiment of the water soluble bands of the invention;

[0030]FIG. 5 is a showing similar to FIG. 3 illustrating a secondalternate embodiment of the water soluble bands of the invention;

[0031]FIG. 6 is a side elevational section showing another embodiment ofa stent delivery device according to the invention;

[0032]FIG. 7 is a side elevational section showing yet anotherembodiment of a stent delivery device of the invention in an uncoveredposition;

[0033]FIG. 8 is a side elevational section of the distal end portion ofthe invention of FIG. 7 in the covered position;

[0034]FIG. 8A is a fragment of FIG. 8 showing an alternate embodiment tosecure the slipping sleeve;

[0035]FIG. 9 is a side elevational section of the distal end portion ofthe invention of FIG. 7 in mid-deployment;

[0036]FIG. 10 is a side elevational section of the distal end portion ofthe invention showing the use of a guide catheter to retrieve amisplaced stent;

[0037]FIG. 11 is a side elevational section of a further embodiment of astent delivery device according to the invention;

[0038]FIG. 12 is a side elevational section of a further embodiment of astent delivery device utilizing pistons and showing the position of thepistons when the stent is in the confined position;

[0039]FIG. 13 is a side elevational section of the embodiment of FIG. 12showing the position of the pistons when in the deployed position;

[0040]FIG. 14 is a side elevational section of the distal end portion ofthe embodiments of FIGS. 11 or 12, i.e., a push/pull version or a pistonoperated version, respectively, the stent being in the confinedposition;

[0041]FIG. 15 is a side elevational section of the distal end portion ofthe embodiments of FIGS. 11 or 12, the stent being in the deployedposition;

[0042]FIG. 16 is a side elevational section showing a single layersheath alternate embodiment;

[0043]FIG. 17 is a side elevational section showing another embodimentof the single layer sheath stent delivery device, and

[0044]FIG. 18 shows yet another embodiment of the inventive stentdelivery device.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0045] While this invention may be embodied in many different forms,there are shown in the drawings and described in detail herein specificpreferred embodiments of the invention. The present disclosure is anexemplification of the principles of the invention and is not intendedto limit the invention to the particular embodiments illustrated.

[0046]FIG. 1 shows an embodiment of the inventive stent deliveryapparatus, generally at 10, which is used to deliver the stent in areduced radius delivery configuration to the deployment site in thebody. Apparatus 10 includes an elongate flexible catheter 12, which inthe this embodiment is extruded of a biocompatible and HPC (hydrophilic)compatible material such as a lubricous polyimide or polyethylene. Othersuitable materials for catheter 12 include nylons, urethanes,polypropylene, and PEBAX materials which are compatible with siliconeand/or hydrophilic coatings. It should be understood that while ahydrophilic compatible material is preferred, any biocompatible materialmay be used. The polyethylene or polypropylene, while not themselveshydrophilic can be coated with a hydrophilic material. Therefore, it canbe seen that any biocompatible or HPC compatible material can be used tomake catheter 12. As will be discussed below, the inventive stentdelivery apparatus allows for the outside diameter of the catheter to be5.3 French (F) (0.070 inches or 1.778 mm) or less using a 0.018 inchguidewire, which is a significant profile improvement over prior artsuch as Heyn U.S. Pat. No. 5,201,757 which discloses an outer diameterof 0.12 inches (3.048 mm).

[0047] The distal end portion of catheter 12 has a pair of slippingsleeves 14 and 16 which are used to form a waterproof chamber around astent 17 carried by the catheter. Although this invention will berelated primarily to using the inventive delivery apparatus for deliveryof self-expanding stents, it should be understood that the inventivedelivery apparatus may be used to deliver both self-expanding and nonself-expanding stents, grafts and stent grafts. Stent 17 is aself-expanding stent, and in this embodiment is a so called wovenbraided stent of a type somewhat similar to those disclosed in WallstenU.S. Pat. No. 4,655,771; Wallsten U.S. Pat. No. 4,954,126 and WallstenU.S. Pat. No. 5,061,275. However, the disclosed stent delivery apparatuswill deliver any type of self-expanding stent, such as for example, astent made of any type of resilient metal or plastic, which wouldinclude a shape memory alloy type stent, such as a nitinol stent. Stent17 is shown confined in its reduced radius delivery configuration by aplurality of water soluble bands 18, described further hereinbelow inFIGS. 3-6. Two pair of radiopaque marker bands 20 and 22 are bonded tocatheter 12 with the marker bands of pair 20 being enlarged in diameterso as to additionally be used to aid in preventing stent 17 from movingaxially while on the catheter. The use of radiographic or fluoroscopicimaging techniques to image the radiopaque marker bands to verify thecorrect positioning for stent deployment is well known in the art.

[0048] Slipping sleeves 14 and 16 are shown in FIG. 1 in the uncoveredposition. The slipping sleeves 14 and 16 are made of molded plastic andthe preferred material is a polyolefin copolymer (POC) SURLYNTM. Othermaterials such as fluoropolymers, noncompliant polyethyleneterephthalate (PET); polyimide, nylon, polyethylene, PEBAX or the likemay also be used. In this embodiment, slipping sleeves 14 and 16 aremolded with an approximately 90° knee, shown at 24, and an approximatelya 45° angle at 26. It has been found experimentally that the 90° knee at24 and the 45° angle at 26 more easily allow the sleeve membranematerial to roll over onto itself. Slipping sleeves 14 and 16 are slidover the catheter and bonded to the catheter at 28, as is well known inthe art. The slipping seal 30 is formed a tolerance fit between theinner diameter of the seal 30 and the outer diameter of the cathetershaft.

[0049] A potential problem with a tolerance fit seal design isencountered when the slipping sleeve is restricted and a great deal ofpressure is required to slid the sleeve. In this case, the pressure canbecome great enough to separate the seal and allow fluid to leak betweenthe inner diameter of the seal 30 and the outer diameter of the cathetershaft. In seal design theory, it is a goal to have the integrity of theseal increase as pressure is increased. An embodiment that does this isshown in FIG. 2B by adding member 25. Member 25 is glued to the innerdiameter of the sleeve and has a length protruding under the sleeve, andis therefore called an “L seal”. As pressure is increased in theballoon, the L seal is held more tightly against the outer diameter ofthe catheter, decreasing the possibility of fluid leakage allowingpressure to build and slid the sleeve.

[0050] Manifolds 44 and 46 are used to introduce fluid into lumens 32and 34 respectively. Manifold 48 is used to insert a guide wire 50through central lumen 52, as is well known in the art. Reference numeral54 shows a section of introducer sheath through which the catheter isinserted into a wound and into a vessel or body lumen.

[0051] One advantage the inventive stent delivery apparatus provides isthat once the catheter has reached the deployment site, no furthermovement of the catheter is required to release the stent. All movementrequired to release the stent is internal to the catheter. By avoidingfurther movement of the catheter 12, the introducer sheath 54 is notdisturbed or moved from its body introduction site, which reduces traumato the entrance wound. Also, avoiding further movement of catheter 12minimizes trauma to the endothelium, which is desirable. By avoidingexternal catheter movement to deploy the stent 17, the inventivedelivery apparatus can be used to deliver stents in more tortuousanatomy as well as allow more precise and accurate control.

[0052] Referring now to FIG. 2, the distal end portion of catheter 12 isshown with slipping sleeves 14 and 16 forming a waterproof chamberaround stent 17. Slipping sleeves 14 and 16 are formed of a doubled-oversection of membrane caused by urging seals 30 of sleeves 14 and 16axially toward each other. This causes the membranes to roll over fromtheir position as seen in FIG. 1 onto themselves at knees 24 as is seenin FIG. 2. It can be seen that sleeves 14 and 16 slightly overlap toform a seal. Stent 17 confined to its reduced radius by bands 18 andpositioned between marker bands 20 in the chamber formed by sleeves 14and 16.

[0053]FIG. 3 shows the apparatus of FIGS. 1 and 2 in mid-deployment,i.e. the two center bands being dissolved. Fluid has been introducedthrough manifolds 44 and 46 and into lumens 32 and 34 to enter sleeves14 and 16. The chamber formed by the sealed end 28 and the slipping seal30 of the sleeve is filled through inflation ports 36 and 38 of eachsleeve, respectively. As the fluid pressure builds in sleeves 14 and 16,fluid is forced out through seal 30 causing seal 30 to slid away fromthe stent 17 along the catheter 12, thereby retracting sleeves 14 and 16to expose or uncover stent 17 to body fluids.

[0054] The water soluble bands 18 are preferably a polyethyleneoxide(PEO), but can be polyvinylpryyolidone (PVP); polyvinyl alcohol (PVA);mannitol, complex carbohydrates or the like, and the composition ofindividual bands can be varied as desired. In FIG. 3, the bandssurrounding the medial portion of stent 17 were constructed such thatthey dissolved faster than the outer bands 18, resulting in the medialrelease shown in FIG. 3. This can be accomplished by varying themolecular weights of the compositions, since the lower the molecularweight the faster the band 18 will dissolve. Varying the thickness oradding perforations (discussed below in connection with FIGS. 5 and 6)will also increase the rate of dissolution.

[0055]FIGS. 4 and 5 show alternate embodiments of water soluble bands18. In FIG. 4, the plurality of bands axially spaced along stent 17 asshown in FIG. 2 have been replaced by a single tubular band 60. In theembodiment of tubular band 60 shown in FIG. 4, the band is thinner inthe middle than at either end and will therefore dissolve faster in themiddle, allowing medial deployment. It can be understood that thethickness of band 60 can be varied as desired to allow for a controlledrelease of stent 17 in any manner desired by the physician, such asreleasing the stent starting from either the proximal or distal end orin other sequential deployments. It should also be understood that band60 can be of the same thickness, but by varying the composition ofpredetermined sections of the band 60, those predetermined sections canbe dissolved at a faster rate, allowing for a controlled release ofstent 17.

[0056]FIG. 5 shows a tubular band 62 which has perforations 64throughout. Perforations 64 are more dense in the middle section of band62 than at either end section, thereby allowing the middle section ofband 62 to dissolve faster, whether composition or thickness is variedor both. Again, the denseness of perforations 64 can be controlledthroughout band 62 to allow for any type of sequential dissolution andself-expansion of stent 17, as desired.

[0057] An alternate embodiment to the use of water soluble bands 18, 60or 62 is to utilize a swelling band or other degradable material whichis attached to the catheter 12. This swelling band material can becomplex carbohydrates, cellulose, crosslinked PVA/PVP,polyethylene/acrylic acid or the like. Self-expanding stent 17 ispressed into the swelling band material, which after curing, will holdstent 17 in its reduced radius delivery configuration. Retractingsleeves 14 and 16 exposes the swelling band material to body fluids,which will expand or swell, releasing the stent 17 to self-expand.Because the swelling band material is attached to the catheter 12, itwill be withdrawn from the body along with the catheter. It should beunderstood that the composition of the swelling material could be variedto control the expansion of stent 17 as above.

[0058]FIG. 6 shows another embodiment of the stent delivery device inwhich the sleeves 14 and 16 have been replaced by a retractable sheath66. Retractable sheath 66 can be withdrawn using a wire as discussedbelow in connection with the push/pull sleeve and hydraulic sleeveembodiments. Retraction of sheath 66 allows body fluid to access anddissolve band 60. It should be understood that the variations of watersoluble or swelling material described above can be used in connectionwith this embodiment.

[0059] One of the important features of the inventive stent deliveryapparatus is that it allows the physician to deploy the stent in avariety of ways. For example the stent can be medially deployed,deployed starting from the distal end of the stent or deployed startingfrom the proximal end of the stent. With medial deployment, either theproximal or distal end of the stent can be released from its sleevefirst or they can both be released at the same time, which providesmaximum flexibility to the physician.

[0060] This deployment flexibility can be accomplished in several ways.One version shown in FIG. 1 is the use of separate lumens 32 and 34 forinflating slipping sleeves 14 and 16, through inflation ports 36 and 38,to allow individual control over each sleeve 14 and 16. This is bestseen in FIG. 2. Another version is shown best in FIG. 2A, where both theproximal inflation port 36 and the distal inflation port 38 share thesame lumen, which allows for a decreased profile. In the shared lumenversion, there are several ways to control the movement of sleeves 14and 16. Sleeves 14 and 16 can be sized differently, as shown in FIG. 1,such that equal sleeve inflation will cause the distal sleeve 16 torelease the distal end of stent 17 before the proximal end of stent 17is released by the proximal sleeve 14. The tightness of seal 30 of eachsleeve can be varied as well by controlling the immersion time andtemperature in the hot water bath. Also, speed control bumps 42 orridges can be formed in the catheter 12 (best shown in FIG. 3) toindividually control the slipping of each sleeve 14 and 16. The sleeveouter diameter could also be varied, which would vary the movement ofthe slipping sleeves. Of course, all of the various techniques could beeasily combined as well by those skilled in the art.

[0061] It should also be noted that although preferred, the watersoluble bands are not required in the embodiment of FIG. 1. Sleeves 14and 16 can optionally be used to contain stent 17 as disclosed inWallsten U.S. Pat. No. 4,732,152; Wallsten U.S. Pat. No. 4,848,343 andImbert U.S. Pat. No. 4,875,480. The same means used to cause sleeves 14and 16 to retract will also permit the stent to self-expand as sleeves14 and 16 are retracted. It should also be understood that the varioustechniques of varying the sleeve lengths of sleeves 14 and 16, thetightness of the slipping seal 30, the outside diameter of sleeves 14and 16, placement of speed control bumps 42 on catheter 12 andindividual lumens for each of the sleeves 14 and 16 allow for greatcontrol over the movement of sleeves 14 and 16, with or without watersoluble band(s) 18, 60 or 62.

[0062] Referring now to FIGS. 7-10, yet another embodiment of the stentdelivery device is shown in which a single slipping sleeve 70 is shownin the uncovered position (FIG. 7). The distal end of sleeve 70 iscontained by cylindrical gripping means 72, which is made of siliconerubber, latex or the like, and is bonded to catheter 12 with an open endoriented toward the sleeve and the stent to receive them as best seen inFIG. 8. The stent 17 may, but need not, extend into gripping means 72along with sleeve 70. FIG. 8 shows the device in the covered positionwith the stent 17 confined to its reduced radius delivery configuration.It should be understood that this embodiment, like those disclosed abovecan optionally use water soluble band(s) 18, 60, 62, a swelling materialor other degradable material to confine stent 17, or stent 17 can beheld in its reduced delivery configuration by sleeve 70 alone.

[0063] An alternate embodiment of the invention of FIGS. 7-10 replacesthe cylindrical gripping means 72 with the embodiment shown in FIG. 8A.In this case the gripping means 72 has been replaced with a silicon ball73 that allows the sleeve to be rolled over it to create a water tightseal. Other materials and shapes can be used that have a desired degreeof compliance with the slipping sleeve.

[0064]FIG. 9 shows the device in mid-deployment. Retraction of sleeve 70has pulled stent 17 from gripping means 72 and allowed stent 17 toself-expand as shown.

[0065]FIGS. 10A and 10B show a technique for recovering a misplacedstent prior to completely releasing the stent shown in FIG. 9. A guidecatheter or other tubular sheath 76 is advanced to surround sleeve 70and partially deployed stent 17, then the entire assembly is withdrawnfrom the body lumen.

[0066] Referring now to FIG. 11, another embodiment of a stent deliverydevice is shown which uses push/pull wires to move a pair of sleeves.Catheter 12 can be seen to have three lumens in sectioned view 11A, acenter lumen 52 for guide wire 50, a proximal lumen 80 for proximal pullwire 82 and a distal lumen 84 for distal push wire 86. Sectioned view11B shows that the catheter has a skived cross-section to allow proximalwire 82 to leave the lumen and to attach to proximal sleeve 88. Distalwire 86 leaves its lumen and attaches to distal sleeve 90 at 92. Byappropriately pushing on a handle 93 attached to distal push wire 86,and pulling on a handle 95 attached to proximal pull wire 82, thephysician can release stent 17. This arrangement also allows controlover which end of the stent is released first. Both wires 82 and 86 maybe teflon coated to lessen the friction caused by movement in theirrespective lumens.

[0067] Referring now to FIGS. 12 and 13, another embodiment of a stentdelivery device is shown which uses hydraulic pressure to move a pair ofsleeves. FIG. 12 shows catheter 12 proximally of the distal end with adistal piston 90 in lumen 92 and a proximal piston 94 in lumen 96. Wires98 and 100 extend from the pistons 90 and 94, respectively, to attach tothe sleeves 90 and 88 as in the previous embodiment. Wire 100 extendsthrough a fixed seal 102. FIG. 13 shows this embodiment in the deployedposition, where fluid pressure in lumen 92 has pushed distal pistondistally, thereby pushing distal sleeve 90 distally. Once distal pistonis past access port 104 the fluid will enter lumen 96 and force proximalpiston proximally in lumen 96, thereby pulling proximal sleeve 88proximally.

[0068]FIGS. 14 and 15 show the distal end of the catheter for both theprevious two embodiments in both the confined and deployed positions.Catheter securing balloons 106 can be optionally inflated prior todeployment to aid in preventing catheter movement during deployment byfrictionally engaging vessel wall 108. Balloons 106 are made from a morecompliant material such as latex, silicone or the like, and are wellknown in the art. Catheter securing balloons 106 can be used inconnection with any of the embodiments by simply adding the appropriatelumens or access from existing fluid lumens. The catheter can also besecured in the vessel by means of a magnet attached to the proximal endportion of the catheter and guidewire, with the guidewire secured usinga magnet external of the body.

[0069] Once the stent is deployed using any of the embodiments, aplacement balloon 110 (best seen in FIG. 9) can be inflated to seat thestent into the vessel wall, as is well known in the art. It should beunderstood that the placement balloon, as well as a partially deployedstent, if desired, can be recovered using the push/pull wire embodiment.For the other embodiments, if necessary a guide catheter or sheath canbe advanced to retrieve the placement balloon or partially deployedstents.

[0070] It has been found that delivering an uncovered stent to adeployment site can damage the vessel wall, due to the sharp edges ofthe stent. It has also been found that an uncovered stent may moveaxially along the catheter and may even slide off the catheter.Therefore the inventive delivery system can also advantageously be usedto deliver a non self-expanding stent to a deployment site safely sincethe stent is covered and prevents movement of the stent, relative to thecatheter, before deployment. A non self-expanding stent can be deployedby using a placement balloon of the type shown in FIG. 9 (reference 110)to expand stent 17, as is well known in the art.

[0071] Referring now to FIG. 16, a single layer sheath embodiment of thestent delivery device is shown in which reference numeral 32 is a fluidlumen for providing fluid through fluid access port 200 to the slippingsleeve 202. Adhesively attached to the slipping sleeve 202 is the singlelayer sheath 204 which can retain the stent 17 in its deliveryconfiguration. The stent is secured between stent bumper 206 and fluidtight seal 208. As fluid is pumped through lumen 32 into slipping sleeve202, the slipping seal 30 moves axially away from the stent 17,retracting the single layer sheath 204 and allowing the stent 17 toself-expand. Stent 17 may optionally be surrounded by a dissolving bandor pressed into a swelling band, as discussed above, the band acting torestrain the stent 17 in its delivery configuration. Retraction of thesingle layer sheath 204 allows fluid access to the dissolving orswelling band, which allows the stent to self-expand in a controlledmanner as discussed above. The single layer sheath may be made from thesame materials and in the same manner as discussed above in connectionwith the slipping sleeves.

[0072] Referring now to FIG. 17, an alternate embodiment of the singlelayer sheath stent delivery device is shown in which reference numeral32 is a shared fluid lumen for providing fluid through fluid accessports 200 and 201 to the slipping sleeves 202 and 203. Separate fluidlumens can also be provided as in FIG. 1 to allow individual controlover each slipping sleeve. Adhesively attached to the slipping sleeves202 and 203 are the single layer sheaths 204 and 205 which can retainthe stent 17 in its delivery configuration. The stent 17 is securedbetween stent bumpers 206 and 207 and the single layer sheaths 204 and205 may abut to provide a fluid tight seal, if desired. As fluid ispumped through lumen 32 into slipping sleeves 202 and 203, the slippingseals 30 move axially away from the stent 17, retracting the singlelayer sheaths 204 and 205, allowing the stent 17 to self-expand. Stent17 may optionally be surrounded by a dissolving band or pressed into aswelling band, as discussed above, the band acting to restrain the stent17 in its delivery configuration. Retraction of the single layer sheaths204 and 205 allows fluid access to the dissolving or swelling band,which allows the stent to self-expand in a controlled manner asdiscussed above.

[0073] Applicants' have discovered experimentally that the 45° knee 26(discussed above) in the slipping sleeve is sometimes weakened due tothe forces acting on the 45° section of slip seal 30. Therefore, toprovide additional strength, the embodiments of FIGS. 16 or 17 may beformed with 90° knees 210, with the knee filled with a cone shapedadhesive ridge 212 shown in FIG. 17. The adhesive ridge 212 supports the90° knee 210 and provides a smooth 45° transition zone which more evenlytransfers the force to the slip seal 30.

[0074] Referring now to FIG. 18, an alternate embodiment of theinvention is shown in which the self-expanding stent is anyself-expanding stent made of a resilient metal or plastic material,which would include shape memory metal stents such as nitinol stents,which are well known in the art. The self-expanding stent is retained inits reduced delivery radius using a collagen sleeve, liner or both.

[0075] Applicants have a copending application entitled “IMPROVED TISSUESUPPORTING DEVICES” filed May 19, 1994 as Ser. No. 08/246,320 whichdiscloses a preferred stent. The entire contents of Ser. No. 08/246,320are hereby incorporated by reference. The stents described in thisapplication are generally cylindrical or tubular in overall shape and ofsuch a configuration as to allow radial expansion for enlargement.Furthermore, the stents are comprised of at least one component whichexhibits a resiliency or spring-like tendency to self-expand the deviceand at least one other component which is deformable so as to allow anexternal force, such as a balloon positioned within the body of thedevice, to further expand it to a final desired size. Preferably, thestents are made of metal and most preferably of shape memory alloys.

[0076] In its broader concept, the device, such as a stent of Ser. No.08/246,320 is made of a first component which is a resilient spring-likemetal for self-expansion and the second component is a deformable metalfor final sizing. In the more preferred shape memory embodiment, thefirst component is a self-expanding austenitic one and second is anmartensitic one capable of deformation.

[0077] The most preferred embodiment the device described in Ser. No.08/246,320 is a stent, preferably of shape memory alloy. The mostpreferred shape memory alloy is Ni—Ti, although any of the other knownshape memory alloys may be used as well. Such other alloys include:Au—Cd, Cu—Zn, In—Ti, Cu—Zn—Al, Ti—Nb, Au—Cu—Zn, Cu—Zn—Sn, Cu—Zn—Si,Cu—Al—Ni, Ag—Cd, Cu—Sn, Cu—Zn—Ga, Ni—Al, Fe—Pt, U—Nb, Ti—Pd—Ni,Fe—Mn—Si, and the like. These alloys may also be doped with smallamounts of other elements for various property modifications as may bedesired and known in the art.

[0078] The stent used in connection with any of the embodimentsdescribed herein is preferably the two component stent described above.However, a typical memory metal self-expanding stent, such as a nitinolstent, may also be used. Any type of self-expanding stent, whether madeof a resilient metal or plastic material, may be used. The term nitinolis intended to refer to the two component memory metal stent discussedabove as well as any other type of known memory metal stent.

[0079] Applicants have found that in delivering a self-expanding stent,such as the preferred two component nitinol stent described above, asthe stent is moved through the body carried by the catheter, the bodytemperature of the patient may heat the nitinol stent to its transitiontemperature, causing it to self-expand. This is considered undesirablebecause it can exert an outward force on the various sheaths discussedabove in connection with FIGS. 1-18 which prevent fluid from hydratingthe stent.

[0080] It is also known to insert a stent at the proximal end of thecatheter, and push the stent through a lumen inside the catheter and outthe distal end of the catheter at the deployment site. Such a device isdisclosed for example in European Patent Application EP 0 556 850 A1,published Aug. 25, 1993. As the stent is moving through the lumen of thecatheter, the body temperature of the patient may heat the nitinol stentto its transition temperature, causing it to self-expand. This canincrease the frictional engagement of the stent with the lumen of thecatheter, making it difficult to push down the length of the catheter tothe delivery site at the distal end.

[0081] Applicants overcome this problem by surrounding the stent with anouter sleeve of water swelling material, such as collagen, lining theinside of the stent with a swelling material, or both. This alternateembodiment may be used in connection with the various embodimentsdiscussed above in connection with FIGS. 1-17 to eliminate the outwardself-expanding force exerted by an type of memory metal stent after ithas reached its transition temperature.

[0082] Referring now to FIG. 18, the water swelling sleeve and/or linerdiscussed above is shown in a stent pusher embodiment. The catheter isreferred to generally at 300 and the guidewire at 302. Theself-expanding stent, including its collagen sleeve, liner or both isshown generally at 304, axially surrounding the guidewire. Stent pusher306 is used to push the stent through the lumen of catheter 300 and outthe distal end of the catheter to the delivery site. In the preferredembodiment, the water swelling material is formulated so that it is slowto hydrate to allow sufficient time to deliver the stent to thedeployment site. Alternatively, a means could be included which wouldprevent the stent from being hydrated until the collagen sleeve and/orlined stent was delivered to its deployment site.

[0083] The stent can be surrounded by an outer sleeve of water swellingmaterial, which in this embodiment is preferably collagen. The stent canoptionally also be held in its reduced delivery configuration by a linerof collagen which is inside the stent. Finally, the stent can optionallyuse both the outer sleeve and the inner liner.

[0084] The collagen sleeve may be of collagen per se or it may becarried on a support such as DACRON® fabric or the like as is known anddisclosed for example in U.S. Pat. Nos. 5,256,418, 5,201,764 and5,197,977, the entire content of which are all incorporated herein byreference, particularly those portions which relate to the formation ofcollagen tubes. The support may be a fabric, woven or braided, and mayalso be of polyester, polyethylene, polyurethane or PTFE. The term“collagen material” is used herein to refer to both supported andunsupported collagen for the sleeve element of this invention.

[0085] The preferred collagen at present appears to be intestinalcollagen believed to be of Type I and Type IV, and in particular acollagen known as Small Intestine Submucosa (SIS) which has particularuse herein, alone and in combination with other collagen material suchas Type I. SIS is predominantly a Type IV material. It is described indetail in U.S. Pat. Nos. 4,902,508; 4,956,178 and 5,281,422, all ofwhich are incorporated herein by reference. In addition to SIS, with orwithout Type I, the collagen may also be made of Type III or Type IV orcombinations thereof. U.S. Pat. Nos. 4,950,483, 5,110,064 and 5,024,841relate to collagen productions and are incorporated herein by reference.Collagen can be extracted from various structural tissues as is known inthe art and reformed into sheets or tubes and attached to a fullyexpanded stent, by for example, wrapping the stent with the collagen andattaching the collagen to itself or by weaving the collagen through theopenings in the stent and attaching it to itself. The stent is thenmechanically pulled down to its reduced diameter and the collagen isdried, which holds the stent in its reduced diameter. The collagen mayalso be dried onto the unexpanded stents mentioned above.

[0086] As such, stent sleeves and/or liners constructed of thesematerials can be used for reservoirs for pharmaceutical agents and thelike. Hydrophilic drugs such as heparin or hirudin to protect againstcoagulation or hydrophobic drugs such as prostaglandins or aspirin andvitamin E may be used to protect against platelet activation. Vitamin Eand other anti oxidants such as sodium ascorbate, phendies, carbazoles,and tocotrienols may be used to protect against oxidation. Mostpreferably, the collagen material will include a quantity of drugmaterial such as heparin which may be incorporated into the collagen inknown manner for release after placement of the stent. Generally, thedrug materials may include the known antithrombic agents, antibacterialand/or antimicrobial agents, antifungal agents and the like.

[0087] During the formation process of the sleeve or liner, variouscomponents may be added to the solution prior to drying or may be addedseparately after formation of the device. Heparin could be directlyadded to the forming solution as could aspirin. Benzalkonium heparin, amodified form of heparin which makes it more hydrophobic could be usedto coat the formed device or film from a solution of alcohol.Prostaglandins PGI2 or PGE2 may be added from a solution of propanol orpropanol/methylene chloride onto a collagen sleeve formed from anaqueous base. Vitamin E could be added from even less polar solutions aschloroform. Other agents could be similarly added. The term “agents” isused herein to include all such additives.

[0088] Cells of the blood vessel wall synthesize and secrete severalkinds of macromolecules forming extracellular matrix. The components ofthis matrix comprise several large proteins that may be syntheticallyconstructed to form films, tubes or multilayer sheets or otherconstructs. Among these biological components are collagens of severaltypes, elastin, glycosaminoglycans (GAGS), fibronectin and laminin.Collagens are three chain glycoproteins with molecular weights of about300,000. Elastin is an insoluble nonpolar amino acid rich crosslinkedprotein. The GAGs are linear chain polysaccharides with various negativecharges with various molecular weights ranging from thousands tomillions. Included in the GAGs are heparin and heparin sulfate, dermatinsulfate and chondroitin sulfate. Fibronectin is a 440,000 MW 2-chainadhesive glycoprotein that acts as a substrate for many cell types andin cell-cell interactions. Laminin is a 2 chain glycoprotein of MW about850,000 and acts as a basement membrane structure for cellular-molecularinteractions. Each of these macromolecules may be combined in amultitude of combinations to form composites. These are all naturalmaterials that serve specific functions and are exposed to blood undernormal repair conditions. It is therefore expected that, if a coveringsleeve for a stent were made of these macromolecules and used in thecourse of intervention, repair of a blood vessel would proceed morenaturally than if a similar device were constructed of syntheticpolymers such as polyethylene, polyteraphthalate or polyurethanes.Macromolecules are also referred to herein generally as “collagen”. Inthis patent collagen thus refers to not only the specific class ofmacromolecules known as collagen but those natural materials thatnormally or naturally form membranes with collagen as laminin,glycosaminoglycans, proteoglycans, pure carbohydrates, fibrin,fibronectin, hyaluronic acid or the like, and other natural materialsthat come into contact with collagen that could be made into film asalbumin, globulins, and other blood borne proteins. Tubular films madefrom any combination of the above materials could provide substantiallythe same purpose as that of pure collagen.

[0089] The collagen sleeve/liner discussed above could also be used withthe embodiments disclosed above in connection with FIGS. 1-17. Forexample, the retractable sheath 66 discussed above in connection withFIG. 6 could prevent fluid access to the collagen material until a wireis used to retract the sheath 66, allowing fluid to access the collagenmaterial, allowing it to swell.

[0090] It should also be understood, that the collagen material remainsin the body, whether as a sleeve surrounding the stent, a liner insidethe stent or both, to aid forming of a non-thrombogenic cushion for thestent in the vascular lumen as well as a natural substrate forendotheliazation. It should also be understood that the dissolving bandembodiments discussed above could also be used as an alternative to theswelling band material such as collagen, but are not preferred sincethey do not remain behind as a non-thrombogenic agent.

[0091] This completes the description of the preferred and alternateembodiments of the invention. It is to be understood that even thoughnumerous characteristics and advantages of the present invention havebeen set forth in the foregoing description, together with the detailsof the structure and function of the invention, the disclosure isillustrative only and changes may be made in detail, especially inmatters of shape, size and arrangement of parts within the principals ofthe invention, to the full extent indicated by the broad, generalmeaning of the terms in which the appended claims are expressed. Thoseskilled in the art may recognize other equivalents to the specificembodiment described herein which are intended to be encompassed by theclaims attached hereto.

What is claimed is:
 1. A delivery system for implantation of a stent ina vessel, comprising: an elongate flexible catheter having proximal anddistal ends for delivering a self-expanding stent to a predeterminedlocation in a vessel; a self-expanding stent having proximal and distalends, the stent surrounding the flexible catheter near its distal end,the stent being in a delivery configuration where the stent has areduced radius along its entire axial length; swelling band stentretaining and release means for retaining the stent in the deliveryconfiguration and for deploying the stent, comprised of at least oneband made of a water swelling material, which holds the self-expandingstent in its delivery configuration against the outwardly urging forceof the self-expanding stent; band protection sleeve means extending overthe entire axial length of the stent to prevent fluid access, andretraction means for retracting the band protection sleeve means overthe entire axial length of the stent, allowing fluid to access and swellthe band, thereby releasing the stent to self-expand.
 2. The deliverysystem of claim 1 wherein the self-expanding stent is a nitinol stent.3. The delivery system of claim 2 wherein the nitinol stent reaches itstransition temperature before the distal end of the catheter reaches thedelivery site, and where the swelling band retains the stent in itsreduced delivery radius.
 4. The delivery system of claim 3 wherein theswelling band material is collagen.
 5. The delivery system of claim 4wherein the collagen swelling band takes the form of a tubular outersleeve of collagen which axially surrounds the stent.
 6. The deliverysystem of claim 4 wherein the collagen swelling band takes the form of atubular inner liner of collagen which lines the inside of the stent andwhich retains the stent in its reduced delivery radius.
 7. The deliverysystem of claim 5 or 6 wherein the collagen is treated with a drug.
 8. Adelivery system for implantation of a stent in a vessel, comprising: anelongate flexible catheter having proximal and distal ends fordelivering a self-expanding stent to a predetermined location in avessel; a self-expanding stent having proximal and distal ends, thestent being carried inside the catheter and is delivered by pushing thestent through the catheter to the distal end and out of the distal endusing a stent pusher, the stent being in a delivery configuration wherethe stent has a reduced radius along its entire axial length; swellingband stent retaining and release means for retaining the stent in thedelivery configuration comprised of at least one band made of a waterswelling material, which holds the self-expanding stent in its deliveryconfiguration against the outwardly urging force of the self-expandingstent until the stent is delivered and where the fluid to swells theband, thereby releasing the stent to self-expand.
 9. Delivery system forimplantation of a self-expanding stent in a vessel, comprising: elongateflexible catheter means having proximal and distal ends for delivering aself-expanding stent to a predetermined location in a vessel; aself-expanding stent having proximal and distal ends, the stentsurrounding the flexible catheter near its distal end, the stent beingin a delivery configuration where the stent has a reduced radius alongits entire axial length; stent retaining and release means for retainingthe stent in the delivery configuration and for deploying the stent, thestent retaining and release means selected from the group consisting ofdissolving bands, slipping sleeves, hydraulic sleeves, push/pull sleevesand swelling bands; wherein the dissolving band stent retaining andrelease means is comprised of at least one water soluble bandsurrounding the stent and retaining the stent in the deliveryconfiguration; band protection sleeve means extending over the entireaxial length of the stent to prevent fluid access, and retraction meansfor retracting the band protection sleeve means over the entire axiallength of the stent, allowing fluid to access and dissolve the band,thereby releasing the stent to self-expand; wherein the slipping sleevestent retaining and release means is comprised of at least one sleeveretaining the stent in the delivery configuration, the sleeve beingformed of a double walled section of sleeve folded over onto itself,with the end of the sleeve nearest the stent being fixedly connected tothe catheter means and the other end of the sleeve connected to thecatheter means with slip seal means and further including inflationmeans for inflating the sleeve with fluid, wherein increased fluidpressure in the sleeve causes the slip seal means end of the sleeve tomove axially away from the stent, shortening the double walled sectionof the sleeve, thereby releasing the stent to self-expand; wherein thehydraulic sleeve stent retaining and release means is comprised ofproximal and distal sleeves, each retaining their respective proximaland distal stent portions in the delivery configuration, proximal anddistal sliding seal means each carried inside a lumen of the elongateflexible catheter means and each connected by a wire to its respectiveproximal or distal sleeve and where fluid pressure in the proximal anddistal sliding seal means lumens moves the proximal and distal slidingseal means axially apart, thereby moving the proximal and distal sleevesaxially apart to release the stent to self-expand; wherein the push/pullsleeve stent retaining and release means is comprised of proximal anddistal sleeves, retaining their respective proximal and distal stentportions in the delivery configuration and each connected respectivelyto proximal and distal wires, each carried inside a lumen of theelongate flexible catheter means, the ends of the proximal and distalwires being movable such that the proximal and distal sleeves moveaxially apart to release the stent to self-expand; wherein the swellingbands stent retaining and release means is comprised of at least oneband attached to and surrounding the catheter and which is made of awater swelling material, and where the stent is pressed into and held inits delivery configuration by the water swelling material; bandprotection sleeve means extending over the entire axial length of thestent to prevent fluid access, and retraction means for retracting theband protection sleeve means over the entire axial length of the stent,allowing fluid to access and swell the band, thereby releasing the stentto self-expand.
 10. The delivery system of claim 9 wherein thedissolving band stent retaining and release means is selected from thegroup consisting of plural bands and tubular band, wherein plural bandsare comprised of a plurality of water soluble bands spaced along thestent and each surrounding the stent, the plurality of bands holding thestent in the delivery configuration, and wherein tubular band iscomprised of a tubular sleeve of water soluble material which surroundsthe stent and holds the stent in the delivery configuration.
 11. Thedelivery system of claim 10 wherein the dissolving band stent retainingand release means is constructed and arranged to allow the stent toself-expand in a predetermined manner.
 12. The delivery system of claim11 wherein the stent has a proximal region, a medial region and a distalregion and where the plural bands or tubular band surrounding one ofsaid proximal, medial or distal regions, are constructed so as todissolve faster than the plural bands or tubular band surrounding theother said regions.
 13. The delivery system of claim 12 wherein thewater soluble bands are made from a material selected from the groupconsisting of polyvinylpyrrolidone, polyvinyl alcohol, mannitol, complexcarbohydrates, polyethyleneoxide and mixtures thereof.
 14. The deliverysystem of claim 13 wherein the band protection sleeve means is selectedfrom the group consisting of protective sheath and slipping sleeve,wherein protective sheath is comprised of a watertight sheath meanswhich prevents fluid access to the stent, and which may be retracted toallow fluid access to the stent, thereby dissolving the plural bands ortubular band to release the stent for self-expansion; and whereinslipping sleeve is comprised of proximal and distal sleeves, each sleevebeing formed of a double walled section of sleeve folded over ontoitself and wherein the two sleeves abut to form a watertight seal whichprevents fluid access to the stent, and which may be retracted to allowfluid access to the stent, thereby dissolving the plural bands ortubular band to release the stent for self-expansion.
 15. The deliverysystem of claim 14 wherein the tubular band is thinner in one of saidproximal, medial or distal regions whereby the thinner region willdissolve faster.
 16. The delivery system of claim 14 wherein the tubularband is perforated, with a greater density of perforations in one ofsaid proximal, redial or distal regions whereby the more denselyperforated region will dissolve faster.
 17. The delivery system of claim14 including a pair of marker bands which are positioned axially on bothsides of the stent, and which prevent axial movement of the stent. 18.The delivery system of claim 9 further wherein: the dissolving bandstent retaining and release means is comprised of a plurality of watersoluble bands spaced axially along the stent and each surrounding thestent, the plurality of bands holding the stent in the deliveryconfiguration, where the stent has proximal, medial and distal regions,and where the bands in the medial region are constructed so as todissolve faster than the bands in the proximal and distal regions, andwhere the band protection sleeve means is comprised of proximal anddistal sleeves, each sleeve being formed of a double walled section ofsleeve folded over onto itself and wherein the two sleeves abut to forma watertight seal which prevents fluid access to the stent, and whichmay be retracted to allow fluid access to the stent, thereby dissolvingthe plural bands or tubular band to release the stent forself-expansion.
 19. The delivery system of claim 18 further includingplacement balloon means for seating the deployed stent into the vesselwall.
 20. The delivery system of claim 19 further including cathetersecuring balloon means for preventing movement of the catheter in thevessel during deployment of the stent.
 21. The delivery system of claim9 wherein the slipping sleeve stent retaining and release means iscomprised of proximal and distal sleeves, retaining their respectiveproximal and distal stent portions in the delivery configuration andwherein increased fluid pressure in the sleeves causes the slip sealmeans ends of each sleeve to move axially away from the stent.
 22. Thedelivery system of claim 21 further including means for individuallycontrolling the movement of each sleeve.
 23. The delivery system ofclaim 22 wherein the means for individually controlling the movement ofeach sleeve is comprised of a separate fluid lumen for controlling theinflation of each sleeve whereby the user may selectively release thedistal end of the stent first, release the proximal end of the stentfirst or release both ends simultaneously.
 24. The delivery system ofclaim 23 further including placement balloon means for seating thedeployed stent into the vessel wall.
 25. The delivery system of claim 24further including catheter securing balloon means for preventingmovement of the catheter in the vessel during deployment of the stent.26. The delivery system of claim 21 wherein the proximal and distal eachshare the same fluid inflation lumen.
 27. The delivery system of claim26 further including means for controlled release allowing release ofeither end of the stent prior to release of the opposite end.
 28. Thedelivery system of claim 27 wherein the means for controlled release iscomprised of varying the sleeve lengths of the proximal and distalsleeves with respect to one another.
 29. The delivery system of claim 27wherein the means for controlled release is comprised of varying thetightness of the seals of the proximal and distal sleeves to thecatheter with respect to one another.
 30. The delivery system of claim27 wherein the means for controlled release is comprised of varying theoutside diameter of the proximal and distal sleeves with respect to oneanother.
 31. The delivery system of claim 27 wherein the means forcontrolled release is comprised of speed control bumps in the cathetermeans.
 32. The delivery system of claim 9 wherein the slipping sleevestent retaining and release means is comprised of a single sleeveretaining the stent in the delivery configuration and sleeve abutmentmeans fixedly attached to the catheter and abutting the distal end ofthe sleeve to prevent fluid access into the slipping sleeve, and whereinincreased fluid pressure in the sleeve causes the slip seal means end ofthe sleeve to move axially away from the stent, pulling the sleeve fromthe distal sleeve abutment means and releasing the stent to self-expand.33. The delivery system of claim 9 further including means forcontrolled release allowing release of either end of the stent prior torelease of the opposite end.
 34. The delivery system of claim 33 whereinthe means for controlled release is comprised of a fluid communicationport between the lumens carrying the proximal and distal sliding sealmeans, and positioned such that increased fluid pressure moves thedistal sliding seal means past the fluid communication port to allowfluid to flow into the proximal sliding seal means lumen, which movesthe proximal sliding seal means proximally, whereby the distal end ofthe stent is release prior to the release of the proximal end.
 35. Thedelivery system of claim 34 further including placement balloon meansfor seating the deployed stent into the vessel wall.
 36. The deliverysystem of claim 35 further including catheter securing balloon means forpreventing movement of the catheter in the vessel during deployment ofthe stent.
 37. The delivery system of claim 9 wherein the push/pullsleeve stent retaining and release means proximal and distal sleeves aresized to allow the distal end to be released before release of theproximal end, whereby the stent may be retrieved if it is misplaced. 38.The delivery system of claim 9 further including placement balloon meansfor seating the stent into the vessel wall, and wherein the stentretaining and release means is used to recapture the placement balloonwhen the stent is fully deployed.
 39. The delivery system of claim 38further including catheter securing means for preventing movement of thecatheter in the vessel during deployment of the stent.
 40. The deliverysystem of claim 39 wherein the catheter securing means is comprised ofballoon means.
 41. The delivery system of claim 39 wherein the cathetersecuring means is comprised of magnet means.
 42. A method of deploying astent utilizing the delivery system of claim 9, comprising the steps of:securing the stent in the delivery configuration using the stentretaining and release means; moving the distal end of the catheter meansto a predetermined deployment site; releasing the stent using the stentretaining and release means.
 43. The method of claim 42 including thefurther step of controlling the release of the stent such that the stentself-expands in a predetermined manner.
 44. The method of claim 43including the further step of inflating a placement balloon to seat thestent into the vessel wall.
 45. The method of claim 44 including thefurther step of recovering the balloon used to seat the stent using thepush/pull sleeve stent retaining and release means.
 46. The method ofclaim 42 including the further step of recovering a partially deployedstent.
 47. The method of claim 42 including the further step of securingthe catheter to prevent movement of the catheter in the vessel duringdeployment of the stent.
 48. Delivery system for implantation of a stentin a vessel, comprising: elongate flexible catheter means havingproximal and distal ends for delivering a stent to a predeterminedlocation in a vessel; stent expansion means surrounding the flexiblecatheter near its distal end; a stent having proximal and distal ends,the stent surrounding the stent expansion means; stent covering meansfor covering the stent, the stent covering means selected from the groupconsisting of slipping sleeves, hydraulic sleeves, and push/pullsleeves; wherein the slipping sleeve stent covering means is comprisedof at least one sleeve covering the stent, the sleeve being formed of adouble walled section of sleeve folded over onto itself, with the end ofthe sleeve nearest the stent being fixedly connected to the cathetermeans and the other end of the sleeve connected to the catheter meanswith slip seal means and further including inflation means for inflatingthe sleeve with fluid, wherein increased fluid pressure in the sleevecauses the slip seal means end of the sleeve to move axially away fromthe stent, shortening the double walled section of the sleeve, therebyuncovering the stent; wherein the hydraulic sleeve stent covering meansis comprised of proximal and distal sleeves, each covering theirrespective proximal and distal stent portions, proximal and distalsliding seal means each carried inside a lumen of the elongate flexiblecatheter means and each connected by a wire to its respective proximalor distal sleeve and where fluid pressure in the proximal and distalsliding seal means lumens moves the proximal and distal sliding sealmeans axially apart, thereby moving the proximal and distal sleevesaxially apart to uncover the stent; wherein the push/pull sleeve stentcovering means is comprised of proximal and distal sleeves, retainingtheir respective proximal and distal stent portions, and each connectedrespectively to proximal and distal wires, each carried inside a lumenof the elongate flexible catheter means, the ends of the proximal anddistal wires being movable such that the proximal and distal sleevesmove axially apart to uncover release the stent.
 49. A method ofdeploying a stent utilizing the delivery system of claim 40, comprisingthe steps of: attaching a stent around the stent expansion means;covering the stent using the stent covering means; moving the distal endof the catheter means to a predetermined deployment site; uncovering thestent, and expanding the stent using the stent expansion means.
 50. Adelivery system for implantation of a stent in a vessel, comprising:elongate flexible catheter means having proximal and distal ends fordelivering a self-expanding stent to a predetermined location in avessel; a self-expanding stent having proximal and distal ends, thestent surrounding the flexible catheter near the flexible catheter'sdistal end, the stent being in a delivery configuration where the stenthas a reduced radius along its entire axial length; stent retaining andrelease means for retaining the stent in the delivery configuration andfor deploying the stent, the stent retaining and release meanscomprising single layer sheath retaining means surrounding the stent forretaining the stent in its delivery configuration, and slipping sleevemeans for releasing the stent to self-expand, the slipping sleeve meansattached to the single layer sheath retaining means, the slipping sleevemeans being formed of a double walled section of material folded overonto itself, and further including inflation means for inflating theslipping sleeve means with fluid, wherein increased fluid pressure inthe slipping sleeve means causes the slipping sleeve means to moveaxially away from the stent, retracting the single layer sheathretaining means, thereby releasing the stent to self-expand.
 51. Thedelivery system of claim 50 wherein one end of the slipping sleeve meansis fixedly connected to the catheter means and the other end of theslipping sleeve means is connected to the catheter means with slip sealmeans and wherein the single layer sheath retaining means is a singleelongate section of sheath material retaining the stent in its deliveryconfiguration, and where the stent is released from an end as the singlelayer sheath retaining is retracted.
 52. The delivery system of claim 50wherein the single layer sheath retaining means is comprised of proximaland distal sections of sheath material, each respectively retaining theproximal and distal portions of the stent in the delivery configuration,and wherein the slipping sleeve means is comprised of proximal anddistal slipping sleeves, each being formed of a doubled over section ofmaterial folded over onto itself, and where the end of each slippingsleeve closest to the stent is fixedly attached to the catheter meansand the other end of each slipping sleeve is connected to the cathetermeans with slip seal means, each slipping sleeve being attached to itsrespective section of single layer sheath retaining material, wherebythe fluid pressure in each slipping sleeve causes the slip seals to slidaxially away from the stent, retracting the sections of single layersheath retaining material, providing medial release and self-expansionof the stent.
 53. The delivery system of claim 52 further includingmeans for individually controlling the movement of each sleeve, whereinthe means for individually controlling the movement of each sleeve iscomprised of a separate fluid lumen for controlling the inflation ofeach sleeve whereby the user may selectively release the distal end ofthe stent first, release the proximal end of the stent first or releaseboth ends simultaneously.
 54. The delivery system of claim 50 furtherincluding dissolving band means comprised of at least one water solubleband surrounding the stent and retaining the stent in the deliveryconfiguration and wherein fluid is allowed access to the dissolving bandmeans by retracting the single layer sheath retaining means, whereby thedissolving band means is dissolved, thereby releasing the stent toself-expand.
 55. The delivery system of claim 50 further includingswelling band means comprised of at least one band attached to andsurrounding the catheter means, which is made of water swelling materialand to which the stent is pressed into and held in its deliveryconfiguration, and wherein fluid is allowed access to the swelling bandmeans by retracting the single layer sheath retaining means, whereby theswelling band means swells, thereby releasing the stent to self-expand.56. A method of deploying a stent utilizing the delivery system of claim50, comprising the steps of: securing the stent in the deliveryconfiguration using the stent retaining and release means; moving thedistal end of the catheter means to a predetermined deployment site;releasing the stent using the stent retaining and release means.
 57. Themethod of claim 56 including the further step of controlling the releaseof the stent such that the stent self-expands in a predetermined manner.58. A delivery system for implantation of a stent in a vessel,comprising: elongate flexible catheter means having proximal and distalends for delivering a stent to a predetermined location in a vessel; astent having proximal and distal ends, the stent surrounding theflexible catheter near the flexible catheter's distal end, the stentbeing in a delivery configuration where the stent has a reduced radiusalong its entire axial length; stent retaining and release means forretaining the stent in the delivery configuration and for deploying thestent, the stent retaining and release means comprising single layersheath retaining means surrounding the stent for retaining the stent inits delivery configuration, and slipping sleeve means for releasing thestent for expansion, the slipping sleeve means attached to the singlelayer sheath retaining means, the slipping sleeve means being formed ofa double walled section of material folded over onto itself, andincluding inflation means for inflating the slipping sleeve means withfluid, wherein increased fluid pressure in the slipping sleeve meanscauses the slipping sleeve means to move axially away from the stent,retracting the single layer sheath retaining means, and balloonexpansion means arranged inside the stent to expand the stent.
 59. Amethod of deploying a stent utilizing the delivery system of claim 50,comprising the steps of: enclosing the stent in the deliveryconfiguration using the stent retaining and release means; moving thedistal end of the catheter means to a predetermined deployment site;releasing the stent using the stent retaining and release means, andexpanding the stent with the balloon expansion means.
 60. A deliverysystem for implantation of a stent in a vessel, comprising: an elongateflexible catheter having proximal and distal ends for delivering aself-expanding stent to a predetermined location in a vessel; aself-expanding stent having proximal and distal ends, the stentsurrounding the flexible catheter near its distal end, the stent beingin a delivery configuration where the stent has a reduced radius alongits entire axial length; stent retaining and release means for retainingthe stent in the delivery configuration and for deploying the stent,comprised of sheath means extending over the entire axial length of thestent which holds the self-expanding stent in its delivery configurationagainst the outwardly urging force of the self-expanding stent;retraction means for retracting the sheath means to release the stent toself-expand, the retraction means comprised of a wire carried in a lumenof the elongate flexible catheter which is attached to the sheath means,whereby retracting the wire retracts the sheath means.
 61. The deliverysystem of claim 60 wherein the sheath means prevents fluid access to thestent prior to retraction and further including band means which holdsthe self-expanding stent in its delivery configuration until fluidaccesses the band means, thereby releasing the stent to self-expand. 62.The delivery system of claim 61 wherein the band means is comprised ofat least one water soluble band.
 63. The delivery system of claim 62wherein the at least one water soluble band is constructed and arrangedto allow the stent to self-expand in a predetermined manner.
 64. Thedelivery system of claim 63 wherein the at least one water soluble bandis a single tubular band surrounding the stent.
 65. The delivery systemof claim 63 wherein the at least one water soluble band is a pluralityof water soluble bands spaced along the stent and each surrounding thestent.
 66. The delivery system of claim 60 wherein the band means iscomprised of at least one swelling band.
 67. The delivery system ofclaim 66 wherein the at least one swelling band is constructed andarranged to allow the stent to self-expand in a predetermined manner.68. The delivery system of claim 67 wherein the at least one swellingband is a single tubular band surrounding the stent.
 69. The deliverysystem of claim 67 wherein the at least one swelling band is a singletubular band into which the stent is pressed.
 70. A method of deployinga stent utilizing the delivery system of claim 60, comprising the stepsof: securing the stent in the delivery configuration using the stentretaining and release means; moving the distal end of the catheter meansto a predetermined deployment site; releasing the stent using the stentretaining and release means.
 71. A delivery system for implantation of astent in a vessel, comprising: an elongate flexible catheter havingproximal and distal ends for delivering a stent to a predeterminedlocation in a vessel; an expansion balloon surrounding the flexiblecatheter near its distal end; a stent having proximal and distal ends,the stent surrounding the expansion balloon; sheath means extending overthe entire axial length of the stent; retraction means for retractingthe sheath means to release the stent for expansion, the retractionmeans comprised of a wire carried in a lumen of the elongate flexiblecatheter which is attached to the sheath means, whereby retracting thewire retracts the sheath means.